Snaps are a common fastener used in many applications, from clothing to large fabric coverings. In particular, snaps may be used to secure protective canvas coverings for boats, tractors, walk-behind snowplows, and the like. In these latter applications, snaps are installed on the canvas so as to be able to attach the canvas to the frame of the item to be covered. The frame will include one side of the snap and the canvas the other. Typically, the frame includes the male portion of the snap, and the canvas the female portion. The female portion includes a cap on one side of the canvas or other fabric, and a socket on the other. The socket is adapted to fit into the cap with the fabric between the socket and the cap, forming the female portion of the snap. The female portion may then mate with the male portion of the snap to complete the fastening. In some applications, the male portion is also mounted on a fabric or canvas by a similar method of pressing the fabric between male caps and sockets.
FIGS. 1A and 1B depict the various pieces involved in snap installation. Fabrics 60 and 62 are to be made to be attachable to one another by snap 46. It is understood that in many instances in practice, the male portion of the snap will be permanently affixed to a hard surface, such as a boat. In this illustration both the male and female snap portions are affixed to pieces of fabric 60, 62 so as to show all possible pieces of snap 46. Female cap 52 and female socket 54 are placed on either side of fabric 60 in a location corresponding to the location of male cap 56 and male socket 58 on fabric 62. Female cap 52 includes pusher 53 that is adapted to push fabric 60 through and mate with hole 55 of female socket 54 (shown in FIG. 1D). Sufficient force must be provided to force female cap 52, fabric 60, and female socket 54 together permanently. Female socket 54 includes a recessed portion depicted in FIG. 1A by dotted lines.
In FIG. 1B, the female and male portions of snap 46 have been affixed to fabric 60 and 62, respectively. FIG. 1B shows integrated female portion 48 and integrated male portion 63. Integrated female portion 48 is female cap 52 and female socket 54, as shown in FIG. 1A, after sufficient force has been applied to permanently mount the female portion of snap 46 onto fabric 60. Integrated male portion 63 is male cap 56 and male socket 58, as shown in FIG. 1A, after sufficient force has been applied to permanently mount the male portion of snap 46 onto fabric 62. As with the female cap 52 and female socket 54 shown in FIG. 1A, dotted lines show that male cap 56 includes an interior hollow portion adapted to mate with male socket 58 through fabric 62. Integrated male portion 63 is placed on either side of fabric 62 in a location corresponding to the location of integrated female portion 48 on fabric 60. Again, sufficient force must be provided to force male cap 56, fabric 62, and male socket 58 together permanently.
FIG. 1C is a perspective view of female cap 52, including pusher 53 and cap rim 57. FIG. 1D is a top down view of female socket 54, including hole 55 and socket rim 59. Although not obvious from the top down view of FIG. 1D, hole 55 is recessed below socket rim 59, as indicated by dotted lines in FIG. 1A.
The mounting of a female or male snap portion onto fabric or canvas requires the use of a tool designed specifically for this purpose. The standard prior art for this purpose is a vice grip type tool that requires the installer to grip the tool with his hand and apply a large amount of squeezing force to securely rivet the cap to the socket. FIG. 2 shows an example of a prior art vice grip type tool. This tool includes a rubber receiver 51 within the metallic top portion of the vice. During snap installation, a female cap 52 is placed within rubber receiver 51 prior to the application of force on the tool. The placement of female cap 52 within rubber receiver 51 is difficult and imprecise. The user must wiggle the female cap 52 around until it seems properly placed within the rubber receiver 51. Often, despite this effort, the female cap 52 is not properly placed, leading to misalignment with the female socket 54 after application of force onto the tool, and the necessity to redo that snap installation in addition to damage to the fabric 60 which will have been unnecessarily punctured. Moreover, the wiggling around of the female cap 52 within the rubber receiver 51 results in the rubber receiver 51 wearing down quickly.
In addition to this design flaw, the force required to properly operate a prior art tool is extremely fatiguing, especially considering that some applications require that the snap be installed through up to four layers of material. This is particularly true for applications requiring the installation of many snaps, such as with a canvas to cover a large boat. The average boat canvas requires the installation of approximately eighty snaps. Even for someone with good strength and dexterity in his hand, this repetitive motion can become difficult, but this is particularly true for those with limited strength or dexterity in their hands. It is well known throughout the canvas enclosure business that the repetitive, excessive squeezing force required to perform this task can lead to injuries to the hand and forearm such as tendinitis, arthritis, bursitis, etc. . . . Therefore there is a need for a snap installation tool that provides the necessary force from a source other than the human hand. Such a source may be electric, pneumatic, or hydraulic, for example.
Electric, pneumatic, and/or hydraulic snap installation devices do exist. U.S. Pat. No. 4,090,652 to Silverbush, for example, discloses a snap fastener attaching system whose operation and control is implemented by means of a control sequencer that can operate by means of electronic or electromechanical relays or by pneumatic devices. The snap fastener attaching system employs a movable carriage assembly that is controlled in linear motion by a belt system coupled to an actuator mechanism. The carriage assembly includes clamping means that are sequentially operated to clamp a garment on the assembly after emplacement by an operator. Although this snap fastener attaching system uses power other than the human hand to provide the force necessary for the snap installation, it is a large, complicated, and stationary device that is ill suited for use in the field, particularly for large applications, such as a canvas boat cover, where the device may need to be moved and set up repeatedly in different locations about the cover.
U.S. Pat. No. 5,463,807 to Hochhausl also discloses an automated attaching machine for attaching fasteners. In this invention, support means carry an upper and lower tool assembly; upper and lower fastener part feed means; and pusher and tool drive means. The upper and lower tool assembly comprises an upper and a lower forward arm rigidly secured in spaced parallel relation by a bridging neck connecting the rear of the arms. The forward ends of the arms carry respectively the axially aligned upper punch and the lower die and the upper, and lower forward arms are horizontally slotted and slidably receive upper and lower pusher elements respectively. The feed means comprises removable hoppers and track which are hung on the support means and conduct the parts respectively to the pusher slots in the arms. The upper and lower tool assembly is removably secured in an opening in the frame or support means and the tool drive means respectively releasably operatively engages the upper punch and the lower die and the pusher drive means releasably operatively engage the upper and lower pusher elements. Preferably, as the tool assembly is installed in its opening, the tool drive means automatically engages the punch and die. By virtue of this structure, the integral upper and lower tool assembly can be released from the drive means and removed readily from its secured position in the support means and readily replaced by a different tool assembly to accommodate different fastener parts. Although this invention does not require hand strength and dexterity to install snap fasteners, it is also a large, stationary machine that is not easily transportable and could not easily be used in the field.
In addition to these stationary machines that use a force other than that of a human hand to install snaps, there exist many handheld power tools that use electricity, pneumatics, and/or hydraulics for force. Common examples of these include nail guns, staple guns, and the like. U.S. Pat. No. 6,729,104 to Marshall also discloses a pneumatic crimping and capping handheld tool, which teaches a hand-held, power-operated or power-assisted, crimping/er or decapping/er tool, for container closures, such as vial caps, has a hollow handle, housing a (pneumatic) piston-in-cylinder actuator, with an external trigger operating an internal control valve, to control connection of an external pressure supply, through an internal distribution block, and displacement of an actuator output rod, coupled, through a pivoted bell crank lever, to a demountable crimper or decapper. No such handheld power tool for snap installation exists, however. U.S. Pat. No. 4,090,652 to Silverbush; U.S. Pat. No. 5,463,807 to Hochhausl; and U.S. Pat. No. 6,729,104 to Marshall are hereby incorporated by reference as nonessential material.
Thus there is a need for a handheld power tool adapted for snap installation and for repetitive use in the field.